Re: Hidden power switch for Widgets?

On 01/25/2015 02:28 PM, Tom Stepleton wrote:
>
> Hi again,
>
> Lately I've been running my 2/10 without the Widget inside. I took it
> out because I wanted to exhibit the machine away from my house, and I
> figured the Widget was just too fragile to transport. In its stead,
> I'm using an external IDEfile hooked up to a parallel port card. The
> silence is nice (my IDEfile uses a CF card); so is not having to worry
> about a 31-year-old spindle eating a bearing while you're running the
> machine.
>
> I haven't replaced the Widget yet, but I'd like to---the Lisa is a
> good place to keep it. The thing is that I'd also like the ability to
> switch between having the drive operating or disabled. It's not too
> hard to pull out the disk cage and connect/disconnect the power and
> data cables, but it would be much better if I could lift up the front
> cover and toggle a switch instead.
>
> I'm not sure what would be required for that to work, but my
> recollection is that it can't be as simple as putting a switch between
> some/all of the power lines and the drive. I think I once tried
> disconnecting just the power connector (and not the data ribbon
> cable), and the green drive LED lit up anyway, even though the drive
> mechanism was still. If that memory is accurate, some of the data
> cable's lines must also need to be disabled to truly leave the Widget
> "off".
>
>

I did something similar with IDE drives on an old G4 Mac tower so I could easily switch between operating systems once. Was just a dual throw switch on the +5V and +12V lines. Worked well. I used a PC IDE cable without the master/slave twist to have both drives on the same channel.

In this case I'd look for any power lines on the data cable, and switch those out too if possible.

I would look into a small reed switch and try to find a place in the Lisa's case where you can place it that isn't blocked by metal - this way, no major modifications, nothing obvious. You'd place a magnet there to activate the reed switch. Alternatively, you could run a microswitch out through one of the vent holes, but it's harder to do without modifying the case, or having something hanging outside.

The trouble with magnets and reed switches is to keep them away from the CRT. For external profiles I originally used a DB25 manual switch, but it's hard to find any of these now, plus even back then, they're were mostly for RS-232, so they didn't have all the wires, and even worse, once I found one that had all the wires, sometimes it didn't work well because it didn't always provide a clean contact without degrading the signal. So, instead, I just piled up my profiles in a stack and manually moved the DB25 cable to whichever I wanted to boot off of... Xenix, LOS, LPW, etc.

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